1. Field of the Invention
This invention relates to an electronic flash device wherein the discharge current is provided to the flash tube directly from a battery and, more particularly, to an electronic flash device which does not include a primary storage capacitor and which instead operates to discharge current through a flash tube directly from a battery.
2. Description of the Prior Art
The Polaroid SX-70 Land camera made and sold by the Polaroid Corporation, Cambridge, Mass., U.S.A. is adapted to make photographs automatically either by ambient light or by the aid of a flash lamp array. It is highly desirable to extend the capabilities of the Polaroid SX-70 Land Camera and other such cameras as the new Polaroid Pronto! Camera for use with electronic flash. One type of electronic flash device or strobe particularly suitable for use with Polaroid's SX-70 Land Camera as disclosed in U.S. Pat. No. 4,074,295, entitled "Compact Accessory Strobe for Cameras with Battery Enclosed Film Pack," by R. Kee, issued Feb. 14, 1978, is directed to a compact strobe which is powered directly from the camera by way of a battery located within a film cassette. This strobe, as well as other strobes, that have been provided for use with such cameras utilize a low voltage battery supply together with a voltage converter circuit for charging a storage capacitor to a relatively high voltage suitable for discharge through a flash tube to provide an illuminating flash of light. The time required for the converter to charge the capacitor to the required voltage is generally of such long duration that the photographer must first turn on a power control switch to energize the electronic flash device and then wait for the voltage converter to charge the storage capacitor to the required voltage before the camera can be actuated to provide a photographic exposure cycle. The photographer is generally made aware of when the electronic flash device reaches a satisfactory charge condition by the turning on of a ready light which signals him that he may now proceed with the actual camera exposure. The time during which the photographer must wait for the electronic flash device to become fully charged prior to actuating the camera shutter button thus presents an obvious disadvantage to the electronic flash in comparison with an ordinary flash lamp.
Most recently, a fast charging strobe has been disclosed in U.S. patent application Ser. No. 930,863, supra, which substantially shortens the time which the photographer must wait for the electronic flash device to become fully charged. The charge time delay is sufficiently short that the capacitor may be fully charged in the minute time delay between the initiation of the photographic exposure and the actual commencement of the exposure interval as occurs in such cameras as Polaroid's SX-70 model.
Therefore, it is a primary object of this invention to provide an electronic flash device wherein the photographer is not required to first turn on the power to the strobe voltage converter and then wait for the strobe capacitor to become fully charged as a precondition to commencing the photographic operation.
It is a further object of this invention to provide an electronic flash device which does not require any time to charge a primary storage capacitor and therefore may be used in the manner of an ordinary flash lamp.
It is another object of this invention to provide an electronic flash device for use with SX-70 Land Cameras and other such cameras wherein the electronic flash device may be ready to flash from the instant that the photographer first depresses the photographic cycle initiating button.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the mechanism and system processing the construction, the combination of elements and the arrangement of parts which are exemplified in the following detailed disclosure.